This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 02077779.3 filed in Europe on Jun. 28, 2002, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to an ink tank for an ink jet printer containing a casing having a bottom and a front wall with an opening formed therein, and a bag accommodated in said casing and collapsible into a sheet-like configuration, wherein the bag has a top wall and a bottom wall, a front edge and a spout formed in a central region of said front edge and located at the position of said front wall opening.
2. Background Art
Several ink jet printers are known to include an ink tank that has a comparatively large volume and is arranged stationarily in the frame of the printer and is connected to a movable ink jet device through a flexible tube. In operation, the ink supply to the ink jet device is achieved either by drawing ink out of the tank or by supplying air to the space inside of the casing but outside of the bag, so that as the bag is collapsed the ink is squeezed out. The supply of ink from the tank to the ink jet device may be assisted by gravitational forces. As an alternative, ink supply might be achieved through gravitational forces alone, provided that the casing can be vented. In any case, the bag prevents the ink from leaking out of the casing and/or from being dried out through contact with the air in the casing.
U.S. Pat. No. 6,264,318 discloses an ink tank of the type indicated above, wherein the bag is disposed in the casing in an upright position so that the front edge of the bag extends vertically. As a consequence, the spout and the corresponding opening in the front wall of the casing must be arranged above the bottom of the casing in a position corresponding to approximately one-half of the height of the casing. This has the drawback that, when the ink is consumed and the bag is gradually emptied, the ink tends to collect in the bottom portion of the bag, below the height of the spout, whereby it becomes difficult to empty the bag completely, without any residues of ink remaining in the bag.
U.S. Pat. No. 6,105,821 discloses a tank in which the spout is formed near a corner of the bag, so that it may be disposed near the bottom of the casing. However, this type of bag is more difficult to manufacture because it is not easy to fix the spout in the seal between the walls of the bag and to seal a fluid-tight manner when the spout is arranged near the corner of the bag. Moreover, since the walls of the bag will be stiffened due to the presence of the spout, it is likely that a pocket will be formed where remnants of the ink may collect, even when the spout is positioned near the bottom edge of the bag. In addition, since the top regions of the bag are relatively far away from the spout, there is the risk that, when the bag collapses, a central portion of the bag is squeezed, so that remnants of ink remain enclosed in the top region. This is why this document proposes the use of a rigid flow inductor fitment disposed inside of the bag.
EP-A-1 013 449 discloses a tank in which the bag is disposed horizontally in a flat casing, so that a major portion of the ink may readily flow out even when the spout is arranged in a central region of the front edge of the bag. On this case, however, the casing must have a relatively large width so as to accommodate the bag. This is particularly disadvantageous when a plurality of ink tanks for different colours are to be disposed side-by-side, in order to be on the same level.